I understand your fear completely.......I felt exactly the same.
As you know, I resisted starting Levadopa for a long time and experimented with Mucuna Pruriens (natural form) first.
I don't know how old you are, but I'm 67 and finally succumbed to the real stuff! My new consultant recommended Madopar and said he had very few patients who developed dyskenesia, jerks and uncontrollable movements after taking it for a long time. I certainly feel much better and have loads more energy and mental capacity. I'm deliberately keeping the dose as low as possible, so my brain doesn't rely on the drugs for all it's dopamine and still produces some of it's own.
I totally know where you're coming from, but only you can decide what to do. As Peter says, he's been on it for 17yrs. and suffers no ill effects. I'm quite encouraged by that! But then we all present and react differently with this wretched PD.
Good luck and let us know what you decide to do. Sorry I've not been much help really.